Unit 3 - Differentiating Mental and Neural Representations Flashcards
Distinguish between mental and neural representations of the world:
Mental representations represent how properties of the outside world are copied/stimulated by cognition, while neural representations refer to the way in which properties of the outside world manifest themselves in the neural signals (i.e., actual encoding of the information in terms of different spiking rates in neurons)
What are grandmother cells?
Hypothetical, highly-specialised cells that respond specifically to very complex and specific stimuli, e.g., one’s grandmother’s face.
What are single cell recordings? Is it invasive? Does it stimulate neural activity? Is it linked to mental or neural representations?
Recordings of the electrical activity within or near one neuron, measuring its spiking rate.
It is invasive, but does not stimulate neural activity.
Neural representations.
Difference between intracellular and extracellular recordings?
Intracellular - electrode placed in the neuron.
Extracellular - electrode placed outside but near the neuron.
What are multi-cell recordings?
Recordings that measure the activity of multiple nearby neurons
What are the three different types of representations at the neural level?
Local representation: specific neurons or groups of neurons encode specific features or concepts
Fully-distributed representation: information is encoded across a large population of neurons, no one-to-one correspondence between neurons
Sparsely-distributed representation: only a small subset of neurons is active at any given time to represent a particular concept or feature
What are the two types of coding, i.e., ways that neurons can represent information?
Rate coding: stimuli/events are associated with a change in the neural firing rate
Temporal coding: information encoded in the precise timing or temporal patterns of action potentials relative to each other
What is EEG? Is it invasive? Does it record and/or stimulate?
Electroencephalography, a non-invasive method that records electrical signals generated by the brain through electrodes that are placed on the scalp.
Non-invasive
Only records
What are reference points in EEG?
Baseline measurements for electrical brain activity, crucial for distinguishing meaningful signals from noise.
Should not be influenced by nor influence the variable under investigation.
Could also be the average of all electrodes.
What are event-related potentials?
Measures of the amount of electrical activity of neurons as a result of stimuli/events. Measured through EEG
How is the spatial resolution of EEG? How about temporal resolution?
Relatively low since the activity at each recorded location cannot necessarily be attributed to neural activity near that region.
Very good temporal resolution
What are some basic requirements for EEG?
A whole population of neurons must be active in synchrony to generate a large enough electrical field.
Neurons in the population must be aligned in a parallel orienting so that their electrical fields can summate and thus generate a detectable signal rather than cancel each other out.
How are the experimental electrodes arranged?
At various locations on the scalp, and labelled according to their location F, P, O, T (frontal, parietal, occipital, temporal, central) and the hemisphere involved (odd nrs left, even numbers right, and “z” for midline)
EEG waveforms reflect neural activity from what parts of the brain? Does all of the activity relate to the current task?
All parts. No, most is spontaneous activity of neurons that do not belong to the task.
What is the signal-to-noise ratio for EEG? How can it be improved?
This is the ratio between the signal being related to the event and noise from the background level of electrical activity.
It can be increased by averaging EEG signals over many presentations of the stimulus.
